Apparatus to automatically retrieve and store commodities stored on shelves is already known.
Such apparatus includes, in general, a commodity transfer platform such as a carriage to move along the storage shelves. Position codes are given to each storage position in the shelves, and a control circuit controls the operation of the commodity carriage by detecting the current storage position of the carriage and by detecting when the carriage reaches the designated storage position. In addition, the prior art apparatus includes a device for transferring commodities between storage positions on the shelves and the commodity carriage and a control circuit to control the complete storage operation.
The known prior art apparatus is able to retrieve a designated commodity and to automatically store a designated commodity by putting in designation code of the commodity at a receiving and delivery section of the apparatus. An example of such known prior art apparatus is illustrated in U.S. Pat. No. 3,526,326.
With the prior art apparatus, the position code for each storage position, necessary to control the position of the commodity carriage, consists of a vertical position code and a horizontal position code. These code marks are arranged in the vertical direction and the horizontal direction along the storage shelves. Code mark scanning devices installed on the carriage, read the code marks and position the carriage in response thereto. The actual position of these prior art code marks and the designated storage positions are not identical due to errors in applying the code marks to the shelves which are evident at the shelf corners. Therefore exact positioning of the carriage may not be achieved, and consequently, it becomes necessary to have a larger storage space than actually required by the volume of commodities to be stored and storage density is decreased.
Furthermore, as the number of storage positions increase, the number of digits or marks in the position code increases and installation of the code marks becomes burdensome.
It is therefore an object of this invention to provide a positioning system for a commodity carriage which can increase the storage density while reducing the complexity of the position code.